The present invention is directed to a tool for setting or leveling the blades in a wood jointer machine. Wood jointers generally include a horizontal worktable having a flat work-supporting and work-feeding surface, and a slot-type opening through the worktable for exposing a rotating cutter head. In use, the workpiece or wood is slidingly passed along the surface of the worktable and as the wood moves across the slot-opening, the blades engage and cut the undersurface of the wood.
The circular rotating cutter head used in jointer or planing machines generally includes a plurality of knife blades that are recessed into the cutting head, being held in place by a plurality of set screws. In order to obtain and maintain production of a precision finished product, the knife blades on the circular cutting head must be leveled on a regular basis. The blades must be leveled so that the cutting edge of the blades engage the surfaze of the workpiece evenly across the piece. Problems inherent in leveling or balancing the knife blades are complicated by the fact that the blades avry in diameter, knife-slot angles vary, knife thicknesses vary, and the base line cuts or cutting circles vary in diamter, and the set screws or other attachment means for holding the blades in the cutting head are of many different types. Consequently, there has previously been no device available which would function on a variety of jointer/planer machines to accurately position a wide variety of cutting blades.
Previous attempts at developing a blade setting device resulted in inventions such as those disclosed in U.S. Pat. Nos. 2,589,865; 2,700,993; and 2,827,711. Each of these patents discloses a device that is attached to the work surface and which includes a means for engaging the knife blades to set the blades at a particular level. Each of these devices must be removed from or otherwise repositioned on the machine in order to be able to rotate the cutter head to move subsequent blades into position for leveling. Each time a blade setting device is removed from the jointer machine, there is some chance that realignment will be compromised and subsequent knife blades will not be leveled in the same plane as previous blades. Understandably, the process of detaching and reattaching the setting tool requires a great deal of time that could be saved if there were a means for rotating the knife blades into position without detaching and realigning the setting tool.
It was to overcoming these problems in leveling the knife blades in a rotating cutter head that the present inventor turned. The resulting present invention is a unique tool which overcomes the above-identified problems and which provides a mechanism for quickly and accurately leveling successive knife blades in a rotating cutter head, without removing the setting tool when rotating the blades into position.
Generally, the present invention includes: (1) a pair of spaced, vertically movable blade stops for contacting and stopping the rotating knife blades when the cutting edge of the blade is at a prescribed height relative to the surface of the horizontal worktable; (2) a jig member having spaced apart gauging surfaces and including means for adjustably supporting the blade stops at the prescribed height; and (3) a means for displacing the blade stops out of the path of rotation of the knife blades after a selected blade has been leveled, and to permit subsequent blades to rotate into position for adjustment.
The jig member itself is a combination of cross bars which enable the jig to be adjustable according to the width of the horizontal worktable, and also to be adjustable with regard to accurately positioning the blade stops over the slot opening at a prescribed point to engage and stop the rotating knife blades. The jig is made of heavyweight metal such as stainless steel and is generally a very simple arrangement of parallel sidebars connected by a movable, elongated crossbar for adjusting the width of the jig. The undersurfaces of the sidebars serve as a gauging surface for the knife blades, with the undersurfaces extended over the slot in a plane corresponding to that of the work-supporting surface of the table. The blade stops are mounted in the forward ends of the parallel side bars and are vertically displaceable for permitting a blade to rotate past the stop.